Thermal relay



July 5, 1932. v v T, GREENWOOD 1,866,032

THERIML RELAY Filed Nov. CSO, 1928 vzo Patented July 5, 1932 i UNITED STATES PATENT OFFICE ,TALMA T. GREENWOOD, OF EAST TEMPLETON, MASSACHUSETTS, ASSIGNOR TO CONDIT ELECTRICAL MANUFACTURING CORPORATION, OFV SOUTH BOSTON, MASSACHUSETTS,

A CORPORATION OF MASSACHUSETTS THERMAL RELAY Application led November at). 19255. Serial No. 322,703.

This invention relates to thermal relays ci the type having a heating element and a thermally expansilile member which is adapted to be heated by said element and expand to B' move either intov or out of cooperative relation with a contact member to control the circuit which includes said contact member.

Heretoore the operative parts of such relays have been built into an enclosing casing,

1 usually of tubular shape, the casing constituting a support in which various components of the relays were independently ymounted and secured in cooperative relation with each other. lt is sometimes necessary to inspect relays of this type either to change the setting of the relays, to clean the contacts, or for various other purposes. This cannot be kdone conveniently when the various parts of the relay are independently mounted on the encloslng casing. In particular, the various parts can not be removed from the casing yand operated under working conditions an their manner of operation ascertained since some of the essential parts, and particularly the stationary contact member, are carried by the casing and the relay is consequently disabled when the casing is removed. n

It 4is an object of the present invention to provide a thermal relay of the general type above set forth. wherein the operative parts of the relay are mounted in a unitary manner on a supporting structure so that the structure can be inserted into and withdrawn from the enclosing casing as a unit and without the necessity for disassembling the working parts of the relay. w f

A further object of theinvention is the provision of a thermal rela-y, having an enclosing casing provided with a plurality of terminals and the operating mechanism ofthe relay mounted as a unitary structure and so arranged that when it is within the casing it is removably connected with the proper 'casing terminals. i f l Another object is generally to improve the construction and operation of thermal relays. Fig. 1 is a side elevation of a thermal relay embodying the invention.

Fig. 2 is an end elevation of a thermal relay supported removably in fuse clips of the cartridge type.

Fig. 3 is a longitudinal sectional elevation of the relay of Fig. 1.

Fi g. l is a section along lines 4-4 of Fig. 3.

Fig. 5 is a erspective view of the removable unit of 1g. 3.

Fig. 6 is a plan detail of the intermediate internal contact of Fig. 3.

As herein shown the thermal relay embodying the present invention includes a tubular insulating casing 10 having screwthreaded ends on which are removably screw threaded end caps 12 and14 which constitute the two line terminals of the relay.

`A ring 16 encircles said insulating casing near one end thereof and is spaced and insulated from both terminal caps and constitutes the third or pilot-circuit terminal of the relay. The end caps 12 and 14 and the intermediate terminal 16 are ada ted to be received in fuse clips 18 of a suitable supporting member 20 for connection with their rein electrical connection with ythe terminals thereof. The unitary relay structure is shown removed from the enclosing casing in Fig. 5 and is showny within the casing in cooperative relation with the terminals thereof in Fig. 3. includes an insulating bar22 which consti. tutes a support for the various parts of the device. A disc 24 is located at one end of said insulating bar. greaterthan the internal diameter of the enclosing casingy 10 and is adapted to lie against one end of said casin within they end cap. 12 and to be clamped re easably against theend of said casing` by vsaid end cap ask shown in Fig. 3. Said disc has, an ear 26 struck .out therefromy andan elongatedk openin 28 vacatedk by the material of said ear. aid ear is relexed at right angles with the body of the disc and is secured lto said insulatingbar by. a. suitable means as the clamping, bolt v30. A second disc 32 is located at the'other end of said bar 22 and has a similar ear 34 Said unitary relay structure Said disc has a vdiameter struck out `at right angles from the body of the disc and' an opening 36 vacated by the material of said ear. Said ear 34 is secured to the end of the bar 22 by suitable means as the attaching bolt 38. Said latter disc has a diameter ap roximately equal to the internal diameter o the insulatin tube so that it can pass reel therethrou h rom one end to the other. Then the re ay structure is located in operative position within the casing the disc 32 is adapted to project slightly beyond the end of the insulating casing so that when the end cap 14 is screwed on the casing it will make firm engagement and electrical contact with said disc.

An electrical heating element herein shown as consisting of a reilexed at strip 40 of resistance material overlies the top face of said insulating bar and has its ends connected electricall with the end discs 24 and 32 by means inc uding the aforesaid bolts 30 and 38. A thermally expansible member 42, consisting of a strip composed of two metals havin dissimilar coeiicients `of expansion secure together back to back, overlies said heater element 40 and is in heat receiving relation therewith. One end of said thermally expansible member is fixedl secured in the aforesaid relation by the a oresaid clamping screw 30 and thus is in electrical connection with the heater element and the disc 24. The free end of said thermally expansible element is provided with a contact member 44. -A generally cylindrical or ring-shaped contact support 45 surrounds the insulating bar 22 and the contact carryin end of the t ermally e ansible element an is fixed to said insulating bar b a suitable means as the screw 46. A portion of said ring is located above the free end of said expansible element and has a downwardly-directed a ertured boss 48 in which a contact 50 is ad]ustably screw threaded. Said contact member 50 is in cooperative relation with the movable contact member 44 of the thermally expansible element whereby, when said element is suitably heated by said heater member 40, it will expand and either make or break its enga ement with the fixed. contact member 50 e-` pendin upon the direction in which. said therma ly ex ansible member is arranged to ileirv when suitabl heated. A rin 52 'is located within and is carried by t e casin underlying the intermediate terminal 16 an and is xed within the casing by suitable means as a rivet 54. Said ring may be provided with one or more downwardly directed s ring lingers 56that are adapted to engage the contact support 45 and thus connect said support and the contact member ,carried thereby electrically with the intermediate terminal 16. As thus arraii d the unitary relay structure asillus'trate in Fig. 5 can be inserted as a unit within the casing and the stationary contact 50 will be automatically located in electrical connection with the intermediate terminal 16 of the casing. When the end caps 12 and 14 are in place the end discs 24 and 32 of the unitary structure are in electrical contact with the end caps so that,

when the relay is inserted in the holding clips of the member 20, it automaticall establishes connection with the circuits o the relay. The operative parts of the relay structure thus are seen to be supported entirel independently of the enclosing casing so that the structure can be withdrawn from the casing and inspected, the contacts adjusted and cleaned, and the operation of the relay observed entirely independently of the casing.

I claim: 1. A thermal relay including the combination of an enclosing casing having terminals removably secured thereto, and a unitary relat least one of which has a screw-threaded connection with said casing, and a unitary 'structure including a support having terminals, separable contact members carried bly said support, anda thermallyexpansible e ement for operating said contact members, said unitary structure being movable into and out of said casing and its terminals being held in detachable en agement with said casing terminals by sai screw-threaded casing terminal.

3. A thermal relay includin the combination of a tubular enclosing casing having end terminals which have removable screwthreaded connections with said casing, and a unitary relay structure movable into and out of said casing having end terminals which have detachable connections with said casing terminals and which are held in engagementwith 'said casing terminals by the screw-'threaded connections thereof with said casin 4. thermal relay having the combination of a tubular enclosing casing having lterminals connected therewith, and a unitary is connected electrically with said terminal relay structure independent* of said casing and its terminals movable 4into and out of said casing as a unit having separable contact members and terminals which have detachable connections with said casing terminals, said casing terminals having means which releasably retains said unit within said casing with the terminals thereof in axial pressure engagement with said casing terminals.

5. A thermal relay having the combination of an enclosing casing having three spaced terminalsconnccted therewith, and a unitaryrelay structure movable asla'unit into and ont of said casing and into and out of engagement with said terminals, said unitary structure including a support, three spaced terminals carried thereb a heater element connected with two of said terminals, a thermally expansible'element carried by said support and connected with one of said terminals, and a stationary contact member cooperating with said expansible element connected with one of said terminals, said terminals having detachable engagements with the terminals of said casing and being retainedin said casing in axial pressure engagement with said casing terminals by one of said casing terminals. y

6. A thermal relay having the combination 20' of an enclosing casing having end terminals and an intermediate terminal connected therewith, and a unitary relay structure removably located within said casing having a support terminals carried by said support detaehably engaged with said end terminals of said casing, an intermediate terminal carried by said support having a detachable cngagement with said intermediate casing terminal, a heater element connected electrically with said support end terminals, -a thermally expansibleelement connected with one of said support end terminals, and a fixed contact member carried by said intermediate of said easing at least one of which has an electrical connection with said expansible member, and means establishing a breakable connection between said fixed contact mem- "support having an intermediate terminal which is detachably connected with said intermediate casing terminal, a fixed contact member carried by said intermediate support terminal, a thermally-expansible member cooperating with said contact member and connected with vone of saidvsupport endv ter-l y i minals, and a heater element connected with both of said support end terminals, said end -caps constituting means to secure said relay tary structure within said casing, which means also constitutes a terminal of said relay.

11; A thermal relay having an enclosing casing, a removable relay unit having a thermo-responsive member, separable contacts controlled by said member, rigidly spaced terminals at the opposite ends of said unit, end caps which are detachably located on thc ends of said casing and bear against said terminals, and means which connects said end caps to said casin g and which forces them axially of the easing against said terminals.

l2. Av thermal relay including the combination of an enclosing casing, a removable relay. unit having terminal members at the ends which engage and center the unit-in the easing, a thermally responsive element and cooperative Contact members controlled there- .by forming a part of said unit, and removable end caps on the ends of the casing which hold the unit therein, at least one of said end caps having a screw-threaded connection with said casing whereby to effect axial pressure ,engagement between said terminal members and end caps.

13. A thermal relay comprising an enclosing casin g, a removable relay unit having end terminalv members, an insulating bar which rigidly connect-s and spaces said members, a

thermo-responsive memberand contacts controlled thereby forming a part of said unit, and end caps which are removably screwthreaded on the ends of said casing and which exert av clamping pressure on said terminal members to retain sald unit `removably 1n said casing and to establish electrical connection between said terminal members and end caps.

14. -A thermal relay including the combination of a tubular enclosing casing open at the ends, a unitary relay that is adapted to be 'inserted and removed through an open end of said casing having endterminal members which are located at the ends of said casing, a thermo-responsive memberand contacts controlled thereby connected mechanically with said end terminal members, a line terminalyforming a closure for one end oi said casing and constituting an abutment for the terminal member' at one end of said relay, and a second line terminal having screwthreaded connection with the opposite end of said easing arranged to close said casing and clamp relay terminals between and into pressure engagement with said casing line terminals.

l5. A thermal relay including the combi nation of a tubular enclosing casing having end terminals, at least one of which has an w axial screw-threaded connection -with said asing, a unitary relay structure removably received in said casing, including a support haring terminals at its ends constituting abutment contact members which are adapted to cooperate with the end terminals of the casing, a thermo-responsive member and separable contacts controlled thereby connected with said support, said screw-threaded terminal constituting clamping means for holding sain relay detachably in terminal engaging position in said casing. 16. A thermal relay'including the combination of a tubular enclosing casing open at one end, a unitary relay structure removably .f received in said casing through the open end thereof including end terminals, a thermorcsponsive device and separable contacts controlled thereby connected mechanically with vsaid end ternmials, and terminal members v5 carried s oi said tubular casing havf l connection with said relay at least one of said casing termi- Aen 'nal aving con action with said casing by ressirely movable axially ot at clamping engagement beand casing terminals. relay including the combiin said casing through the open cluding end terminals and an terini.-al, a thermo-responsive element and separable contact members contrailed hier or forming a part of said strucn tare, terminal members carried by said casing haring ay brealrable connection with the corresponding terminals of said relay, one of said terminal members having a screwthreaded connection with said casing and constituting means to urge said relaystructnre axially oi said casing and similar terminals or" said casing and relay into good electrical engagement.

18. A thermal relay including the combination ot a tubular casing having a terminal intermediate its ends, a unitary relay structure arranged to be inserted into and removed from said casing as a unit including end terminals and an intermediate terminal having a breakable connection with said in- `ing means for effecting pressure engagement between the end terminals of relay and casing.

19. A thermal relay including the combination o an enclosing casing, an end cap on one end of said casing, a relay unit which is insertible in said casing having end terminals one ot which bears against said end ca means rigidly connect-ing and spacing said terminals, a thermo-responsive device and separable contacts controlled thereby connected mechanically with said terminals, and a second end cap Which is screw-threaded onto the other end of said casing and which bears onto said other end terminal and clamps said nnitvbetween it and said first end cap. l

20. A thermal relay including the combination of an enclosing casing, a relay unit having end terminals one or" which is small enough to be removed through said casing and the other of which is too large toenter' said casing, means rigidly connecting and spacing said end terminals, a tliermoresponsive member and separable contacts carried by said means, an end cap which is screenthreaded on one end or" said casing and which clamps said large terminals between it and the end of said casing, and a second end cap which overlies and bears against said small. terminal.

ln testimony whereof, l have signed my name to this specificatie:

TALE/Ll T. GREENWUR. 

